U.S. Secretary of State John Kerry has confirmed that he also will meet with members of Syria's opposition in London.
He spoke to reporters Tuesday at the end of his three-day visit to Israel and the West Bank.
Kerry said the discussion will focus on how to get Syria's President Bashar al-Assad to accept the reality of his situation.
"So, we are left with no choice but to try to find ways to get him to think differently about what lies in the future," said Kerry.
"That will be part of the discussion in London and in the ensuing weeks.''
United Nations Secretary-General Ban Ki-moon urged officials in Damascus to allow a wider U.N. probe into allegations of the use of chemical weapons by both sides in the Syrian conflicts .
Syria wanted an investigation into the alleged use of chemical weapons by rebels in Aleppo.
But it rejected Ban's decision that the probe also should include allegations of the use of chemical weapons by government forces in Homs.
"I appeal to the government of Syria to extend its fullest cooperation and to allow the investigation to proceed.
The mission is ready—they are ready to deploy.
They are waiting in Cyprus," said Ban.
"I sincerely hope that the government of Syria will accept the modalities that I have proposed for the mission.
The Jihadist group al-Qaida in Iraq has confirmed speculations that it is responsible for militant attacks in Syria.
The group posted a statement online declaring its link with the al-Nusra Front in Syria.
France has proposed talks with the European Union and the U.N. Security Council on whether to list Syria's group as a terrorist organization.
The United States already has listed al-Nusra as a terrorist organization.
to make an arrangement or meeting certain, often by phone or writing
eg. His letter confirmed everything.
the state of things as they are, rather than as they are imagined to be
eg. He describes the scene with startling reality.
eg. Both sides suffered heavy casualties in the border armed conflict.
the activity of guessing possible answers to a question without having enough information to be certain
eg. They have much speculation over the cause of the air crash.
someone who uses violent action, or threats of violent action, for political purposes
eg. Without my gun, I'm a sitting duck for any terrorist.